Watercraft are often powered by outboard motors positioned at the stern of the craft. These motors have an internal combustion engine positioned within a cowling of the motor. For among other reasons, because the outboard motor is positioned at the stern of the craft, and because the motor is tiltable, it is desirable to keep the engine's size and weight to a minimum.
These engines are oriented within the cowling such that the crankshaft of the engine is vertically extending. In this arrangement, a cylinder head is positioned at one end of the engine and a crankcase chamber at the other. The combustion chambers are arranged vertically, and the cylinder head has a top end and a bottom end.
Fuel is supplied to the combustion chambers of many of these engines with fuel injectors. These engines typically have the fuel injectors positioned to spray fuel directly into the combustion chamber or into air flowing past the injector through a passage leading to the combustion chambers.
In order to arrange the fuel injectors as described above, the fuel injectors are spaced vertically along the cylinder head from its top to bottom end for projection into the combustion chambers or corresponding adjacent intake passage through the cylinder head. A fuel rail extends along the outside of the cylinder head at that end of the engine for supplying fuel to the fuel injectors. This arrangement causes the engine's profile from its front end to its rear end to increase, causing the entire outboard motor to be larger. This change makes more difficult the tilt or trim function, since the motor's size increases in the same direction as it must be moved.
A fuel injection system for an engine where the injection system does not undesirably increase the profile of the engine, is desirable.